CN109581254B - Phase deviation obtaining method and system and phase calibration method and system - Google Patents
Phase deviation obtaining method and system and phase calibration method and system Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/58—Calibration of imaging systems, e.g. using test probes, Phantoms; Calibration objects or fiducial markers such as active or passive RF coils surrounding an MR active material
- G01R33/583—Calibration of signal excitation or detection systems, e.g. for optimal RF excitation power or frequency
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
- G01R33/3664—Switching for purposes other than coil coupling or decoupling, e.g. switching between a phased array mode and a quadrature mode, switching between surface coil modes of different geometrical shapes, switching from a whole body reception coil to a local reception coil or switching for automatic coil selection in moving table MR or for changing the field-of-view
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/565—Correction of image distortions, e.g. due to magnetic field inhomogeneities
- G01R33/5659—Correction of image distortions, e.g. due to magnetic field inhomogeneities caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field
Abstract
The embodiment of the invention discloses a method for calibrating a digital mode matrix phase, which is characterized by comprising the following steps: acquiring actual phase deviation theta ' of actual phase deviation matrix theta ' constituting a factory-delivered system 'mn(ii) a Calculating an ideal phase deviation forming an ideal phase deviation matrix; calculating a phase deviation of the actual phase deviation from the ideal phase deviation: acquiring the maximum value of the phase deviation; at said maximum value Δ θmaxWhen the phase deviation is smaller than a preset threshold value delta, calculating the phase deviation theta of the field system "mnFrom the field system phase deviation θ "mnThe formed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system; according to the technical scheme, the phase deviation of other rows and columns can be fitted by only acquiring one row and one column in the phase deviation matrix, and the method can be used for quickly calibrating the phase of the system.
Description
Technical Field
The invention relates to a phase calibration method, in particular to a calibration method of magnetic resonance signal space phase.
Background
Digital mode matrices have been widely used in modern magnetic resonance systems, and this new mathematical mode matrix technique does not require any changes in coil hardware design as compared to the conventional hardware mode matrix technique. Although the digital mode matrix implements the same signal conversion as the hardware mode in software, the phase delays from the reception of the magnetic resonance signals to the completion of the analog receiver sampling are different for each coil unit, so that the different delays need to be calibrated.
The existing phase calibration method is based on measurement when a system is installed, and the method is long in time consumption. Obtaining phase calibration data by factory calibration results in extended maintenance time, for example, when recalibration of the phase data is required at the customer site due to the need to replace a particular system component. For this reason, the person skilled in the art is also working to find other phase calibration methods for magnetic resonance systems.
Disclosure of Invention
In view of this, the embodiments of the present invention provide a method and a system for acquiring a phase offset, and on the other hand, provide a method and a system for fast calibrating a digital mode matrix phase by applying the phase offset acquisition method, so as to improve the phase calibration speed of a system located at a customer site.
The phase deviation obtaining method provided in the embodiment of the invention comprises the following steps:
obtaining the path of any input channel j from a coil unit to a coil channel selector in a magnetic resonance system through all output channelsOne line phase deviation to an analog receiver
And acquiring a column phase deviation of all input channels from the coil unit to the coil channel selector from any output channel i to the analog receiver
By said line phase deviation
And column phase deviation
Obtaining the phase deviation from any output channel n to the analog receiver from any input channel m from the coil unit to the coil channel selector in the magnetic resonance system
Obtaining the phase deviation matrix
Value of any one element of
Wherein i, j, m and n are positive integers respectively.
In one embodiment, the line phase deviation is used
And column phase deviation
Obtaining any output channel n from any input channel m from the coil unit to the coil channel selector in the magnetic resonance system to analog receivingPhase deviation of machine
The method comprises the following steps:
with said line phase deviation
And column phase deviation
Respectively as a phase deviation matrix
A row reference value and a column reference value, the phase deviation being described by
Obtaining the phase deviation matrix
Value of any one element of
Wherein the content of the first and second substances,
phase deviation of line
Is selected to be the same as the row element of (a),
is a column phase deviation
Is selected from the group consisting of one column element of,
is a row-column cross element;
m is a positive integer variable, n is a positive integer variable, M, N is the phase deviation matrix respectively
The maximum number of rows and columns.
In one embodiment, the phase deviation matrix
Comprises the following steps:
in one embodiment, the one row element is obtained
The method comprises the following steps: measuring an input phase offset from the coil unit through a jth input channel of the coil channel selector in the magnetic resonance system
And measuring an output phase deviation omega of the magnetic resonance system from the nth output channel of the coil channel selector to the analog receivernThe sum of the two terms is the line phase deviation
Element of (5)
Obtaining the one column element
The method comprises the following steps: measuring an input phase deviation from the coil unit through an m-th input channel of the coil channel selector in the magnetic resonance system
And measuring an output phase deviation omega of the magnetic resonance system from an ith output channel of the coil channel selector to the analog receiveriThe sum of the two terms is the column phase deviation
Column element of (1)
In one embodiment, the any input channel j is a first input channel; the any output channel i is a first output channel;
wherein the content of the first and second substances,
the phase deviation
Is composed of
In one embodiment, the method is also applied to failure analysis of the radio frequency receive link.
The phase deviation obtaining system provided in the embodiment of the present invention includes:
a line phase deviation obtaining module for obtaining the line phase deviation from any input channel j from a coil unit to a coil channel selector in a magnetic resonance system to an analog receiver via all output channels
A column phase deviation obtaining module for obtaining the column phase deviation from all the input channels from the coil unit to the coil channel selector to the analog receiver via any output channel i
A calculation module for passing the line phase deviation
And column phase deviation
Calculating the phase deviation from any output channel n to the analog receiver from any input channel m from the coil unit to the coil channel selector in the magnetic resonance system
Obtaining the phase deviation matrix
Value of any one element of
Wherein i, j, m and n are positive integers respectively.
In one embodiment, the row phase offset acquisition module and/or the column phase offset acquisition module further comprises:
a first measuring unit for measuring an input phase deviation from the coil unit through any one of the input channels of the coil channel selector in the magnetic resonance system;
a second measuring unit for measuring the phase deviation of the output from any output channel of the coil channel selector to the analog receiver in the magnetic resonance system; and
a summation unit for calculating the sum of the input phase deviation and the output phase deviation to obtain the line phase deviation
And/or said column phase deviation
The calibration method for the digital mode matrix phase provided by the embodiment of the invention comprises the following steps:
acquiring actual phase deviation theta ' of actual phase deviation matrix theta ' constituting a factory-delivered system 'mn；
A line phase deviation { theta ] by the actual phase deviation matrix thetajnAnd a column phase offset thetamiCalculating an ideal phase deviation theta forming an ideal phase deviation matrix thetamn；
Calculating the actual phase deviation theta'mnDeviation from said ideal phase θmnPhase deviation Δ θ ofmn：
Obtaining the phase deviation Delta thetamnMaximum value of (a) Δ θmax；
At said maximum value Δ θmaxWhen the phase deviation is smaller than a preset threshold value delta, a line phase deviation { theta ] of a field system is adopted "jnAnd a column phase deviation { theta } "miCalculating the phase deviation theta of the field system "mn(ii) a By phase deviation of the field systemθ”mnThe formed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system;
in one embodiment, the above method further comprises:
at said maximum value Δ θmaxWhen the actual phase deviation is not less than a preset threshold value delta ', the actual phase deviation theta ' is obtained 'mnThe method obtains the phase deviation theta of the field system "mn。
In one embodiment, the actual phase offset θ'mnComprises the following steps:
measuring an input phase deviation from the coil unit through an input channel of the coil channel selector in a factory-delivered system
And an output phase offset ω 'from an output channel of the coil channel selector to the analog receiver'nWill input a phase deviation
And output phase deviation ω'nAdding the two to obtain the actual phase deviation theta 'of the system leaving factory'mn：
Wherein, theta'mnFor the actual phase deviation of the factory system,
is the input phase deviation, ω'nTo output the phase deviation.
In one embodiment, the actual phase deviation matrix θ' is:
wherein the content of the first and second substances,
the input phase deviation of the Mth input channel passing through the coil channel selector from the coil unit in the magnetic resonance system; omega'NThe output phase deviation of the magnetic resonance system from the Nth output channel of the coil channel selector to the analog receiver is obtained, M is the maximum value of the row number of the matrix, and N is the maximum value of the column number of the matrix;
line phase deviation { theta 'of actual phase deviation matrix theta'jnAnd column phase offset { theta'miThe methods are respectively as follows:
θ’jnis the line phase deviation { theta'jnOne row element of theta'miIs the column phase deviation { theta'miOne column element of.
In one embodiment, the ideal phase deviation θmnComprises the following steps:
with the actual phase deviation theta'mnThe line phase deviation of { theta'jnAnd the column phase offset { theta'miAs the line reference values { theta } of the ideal phase deviation matrix theta, respectivelyjn}(0<j is less than or equal to M) and column reference value [ theta ]mi}(0<i ≦ N), the ideal phase deviation θ is obtained by the following equationmnObtaining any element value theta in the ideal phase deviation matrix thetamn：
θmn＝θmi+θjn-θji
Wherein, { theta }jn}＝{θ’jn}；{θmi}＝{θ’mi}；
{θjn}＝{θj1,θj2,…,θjN}，(n＝1,2…N,0<j<M)；
{θmi}＝{θ1i,θ2i,…,θMi}，(m＝1,2…M,0<i<N)；
Wherein theta isjnIs a line reference value { thetajnOne row element of, thetamiIs a column reference value [ theta ]miOne column element of, thetajiIs a row-column cross element; thetamiValue of element, theta, representing column i, row mjnValue of element, theta, representing column n, row jjiThe element value of the jth row and ith column is represented, M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
In one embodiment, the line phase offset is { θ'jnIs a first row phase deviation { theta 'of the actual phase deviation matrix theta'1nI.e. any of the input channels j is selected as a first input channel; the column phase deviation { theta'miIs the phase of the first column of the actual phase deviation matrix theta is different by { theta'm1I.e. any output channel i is selected as a first output channel;
wherein the first row phase deviation { theta'1nIs different from the first column in phase by { theta'm1Are the line reference values { theta } of the ideal phase deviation matrix theta, respectively1nAnd a column reference value [ theta ]m1H, the ideal phase deviation thetamnComprises the following steps:
θmn＝θm1+θ1n-θ11。
in one embodiment, the phase deviation Δ θmnComprises the following steps:
Δθmn＝θ’mn-(θm1+θ1n-θ11)。
in one embodiment, at said maximum value Δ θmaxWhen the phase deviation is smaller than a preset threshold value delta, calculating the phase deviation theta of the field system "mnComprises the following steps:
measuring a line phase deviation of a field system [ theta ] "jnAnd a column phase deviation { theta } "mi}；
Obtained by the following formulaPhase deviation theta of the field system "mn：
θ”mn＝θ”mni+θ”jn-θ”ji
Wherein, theta "miValue of the element, θ, representing the ith column, row m "jnValue of an element representing column n, line j, theta "jiThe element value of the jth row and ith column is represented, M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
In one embodiment, the phase deviation θ' is determined by the field system phase deviation θ "mnThe constructed field system phase deviation matrix theta' is as follows:
wherein M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
In one embodiment, obtaining the actual phase deviation θ 'is employed'mnThe method obtains the phase deviation theta of the field system "mnComprises the following steps:
measuring input phase deviation of input channel from coil unit through coil channel selector in field system
And an output phase deviation omega from the output channel of the coil channel selector to an analog receiver "nNamely:
wherein, theta "mnIs the actual phase deviation of the field system,
for inputting phase deviation, omega "nTo output the phase deviation.
In one embodiment, the field system phase deviation matrix θ "is:
wherein the content of the first and second substances,
an input phase deviation of an Mth input channel passing through the coil channel selector from the coil unit in a field system; omega "NAnd M is the maximum value of the row number of the matrix, and N is the maximum value of the column number of the matrix.
The calibration system for the digital mode matrix phase provided by the embodiment of the invention comprises:
an actual phase deviation obtaining module for obtaining the actual phase deviation theta ' of the factory system constituting the actual phase deviation matrix theta ' of the factory system 'mn；
An ideal phase deviation calculation module for calculating an ideal phase deviation theta forming an ideal phase deviation matrix thetamn；
A phase deviation calculation module for calculating the actual phase deviation θ'mnDeviation from said ideal phase θmnPhase deviation Δ θ ofmn：
Δθmn＝θ’mn-θmn；
A maximum value obtaining module for obtaining the phase deviation delta thetamnMaximum value of (a) Δ θmax；
A judging module for judging the maximum value delta thetamaxWhether the difference is smaller than a preset threshold value delta: and
a field system phase deviation module for calculating a maximum value Δ θmaxWhen the phase deviation is smaller than a preset threshold value delta, the phase deviation theta of the field system is calculated by adopting the phase deviation module of the field system "mnFrom the field system phase deviation θ "mnThe formed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system; wherein m and n are respectively positive integer variables.
In one embodiment, the actual phase offset acquisition module comprises:
a first measuring unit for measuring the input phase deviation of the factory system from the coil unit via any input channel of the coil channel selector
A second measurement unit for measuring output phase deviation ω 'from any output channel of the coil channel selector to the analog receiver'n(ii) a And
a summation unit for calculating actual phase deviation θ'mnI.e. input phase deviation
Is deviated from output phase by ω'nAnd (3) the sum:
in one embodiment, the actual phase offset θ'mnThe actual phase deviation matrix θ' is formed as:
wherein the content of the first and second substances,
the input phase deviation of the Mth input channel passing through the coil channel selector from the coil unit in the magnetic resonance system; omega'NFor the output phase deviation from the Nth output channel of the coil channel selector to the analog receiver in the magnetic resonance system, M is the maximum value of the number of rows of the matrix, and N is the maximum value of the number of columns of the matrix；
Line phase deviation { theta 'of actual phase deviation matrix theta'jnAnd column phase offset { theta'miThe methods are respectively as follows:
θ’jnis the line phase deviation { theta'jnOne row element of theta'miIs the column phase deviation { theta'miOne column element of.
In one embodiment, the ideal phase offset calculation module can be configured to:
with the actual phase deviation theta'mnThe line phase deviation of { theta'jnAnd the column phase offset { theta'miAs the line reference values { theta } of the ideal phase deviation matrix theta, respectivelyjn}(0<j is less than or equal to M) and column reference value [ theta ]mi}(0<i ≦ N), the ideal phase deviation θ is obtained by the following equationmnObtaining any element value theta in the ideal phase deviation matrix thetamn：
θmn＝θmi+θjn-θji
Wherein, { theta }jn}＝{θ’jn}；{θmi}＝{θ’mi}；
{θjn}＝{θj1,θj2,…,θjN}，(n＝1,2…N,0<j<M)；
{θmi}＝{θ1i,θ2i,…,θMi}，(m＝1,2…M,0<i<N)；
Wherein, thetajnIs a line reference value { thetajnOne row element of, thetamiIs a column reference value [ theta ]miOne column element of, thetajiIs a row-column cross element; m is a row of the matrixThe maximum number, N is the maximum number of columns of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
In one embodiment, the field system phase offset calculation module:
for interpreting a maximum value Δ θ at the interpretation modulemaxWhen the line phase deviation is smaller than a preset threshold value delta, measuring the line phase deviation { theta'jnAnd column phase deviation { theta } "mi}；
Wherein the line phase deviation { theta "jnThe method comprises the steps that (1) phase deviation of any input channel j from a coil unit to a coil channel selector in the field system to an analog receiver through all output channels is obtained;
column phase deviation [ theta ] "miThe phase deviation from any output channel i to the analog receiver is obtained by passing all input channels from the coil unit to the coil channel selector in the field system;
the on-site system phase deviation θ' is obtained by the following formula "mn：
θ”mn＝θ”mi+θ”jn-θ”ji
Wherein, theta "miValue of the element, θ, representing the ith column, row m "jnValue of an element representing column n, line j, theta "jiThe element value of the jth row and ith column is represented, M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
In one embodiment, the field system phase deviation module:
also for at said maximum value Δ θmaxWhen the phase difference is larger than a preset threshold value delta, the actual phase difference module is adopted to obtain the actual phase difference theta'mnThe method obtains the phase deviation theta of the field system "mn。
It can be seen from the above solution that, due to the phase deviation acquiring method for a magnetic resonance system proposed by the present invention, the phase deviation of the system can be calculated quickly. In addition, an embodiment of the present invention applies the above method for acquiring a phase offset to fast phase calibration of a magnetic resonance system, and provides a method for determining whether a fast phase calibration method can be used based on historical phase calibration data, so that the phase calibration time can be shortened on the premise of ensuring accuracy. Especially when the engineer needs to acquire the phase deviation again due to hardware replacement in the client site, the method can greatly shorten the maintenance time.
Drawings
The foregoing and other features and advantages of the invention will become more apparent to those skilled in the art to which the invention relates upon consideration of the following detailed description of a preferred embodiment of the invention with reference to the accompanying drawings, in which:
fig. 1 is an exemplary flowchart of a method for obtaining a phase offset according to an embodiment of the present invention.
Fig. 2 is a simplified model diagram of measuring phase offset in an mr system according to an embodiment of the present invention.
Fig. 3 is a block diagram of an exemplary phase offset obtaining system according to an embodiment of the present invention.
Fig. 4 is an exemplary flowchart of a method for calibrating a phase of a digital pattern matrix according to an embodiment of the present invention.
Fig. 5 is a block diagram of an exemplary system for calibrating a digital pattern matrix phase according to an embodiment of the present invention.
Wherein the reference numbers are as follows:
| reference numerals | Means of |
| 101～103,401～406 | Step (ii) of |
| 201 | |
| 202 | |
| 203 | |
| 204 | |
| 205 | |
| 310 | Line phase |
| 320 | Column phase |
| 330 | |
| 510 | Actual phase |
| 311 | First measuring |
| 312 | |
| 313 | Summing |
| 520 | Ideal phase |
| 530 | Phase |
| 540 | Maximum |
| 550 | Judging |
| 560 | On-site system phase deviation module |
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail by referring to the following examples.
Fig. 1 is an exemplary flowchart of a method for obtaining a phase offset according to an embodiment of the present invention. Fig. 2 is a simplified model diagram of measuring phase offset in an mr system according to an embodiment of the present invention. Fig. 3 is a block diagram of an exemplary phase offset obtaining system according to an embodiment of the present invention. A phase offset obtaining method according to an embodiment of the present invention is described in detail with reference to fig. 1 to 3.
In an embodiment of the invention, the simplified model of the phase offset in the magnetic resonance system comprises a coil unit 201, a coil channel selector 202, an analog receiver 203, as well as an input channel 204 for communication between the coil unit 201 and the coil channel selector 202 and an output channel 205 for communication between the coil channel selector 202 and the analog receiver 203.
The coil unit 201 is used for receiving a signal of a system, the signal is transmitted to the coil channel selector 202 through the input channel 204, the signal is transmitted to the analog receiver 203 through the output channel 205, and the analog receiver 203 samples the signal.
According to the simplified model of the phase deviation of the magnetic resonance system, an embodiment of the present invention provides a phase deviation obtaining method, including:
step 101: obtaining a line phase offset of a coil unit 201 in a magnetic resonance system to any input channel j204 of a coil channel selector 202 via all output channels 205 to an analog receiver 203
In particular, the line phase deviation is calculated
There are various methods, one of which is shown below, for example.
In the embodiment of the invention, the line phase deviation
Consisting of several line elements, e.g.
(n＝1,2…N,0<j<M), wherein one line element is obtained
The method comprises the following steps: measuring a phase deviation from the coil unit 201 through a jth input channel 204 of the coil channel selector 202 in the magnetic resonance system
And measuring a phase deviation ω from the nth output channel 205 of the coil channel selector 202 to the analog receiver 203 in the magnetic resonance systemnThe sum of the two terms is the line phase deviation
Step 102: acquiring a column phase deviation of all input channels 204 from the coil unit 201 to the coil channel selector 202 via any output channel i205 to the analog receiver 203
In particular, the column phase deviation is calculated
There are various methods, one of which is shown below, for example.
In an embodiment of the invention, the column phase deviation
Consisting of several column elements, e.g.
Wherein a column element is obtained
The method comprises the following steps: measuring a phase deviation from the coil unit 201 through an mth input channel 204 of the coil channel selector 202 in the magnetic resonance system
And measuring the phase deviation ω from the ith output channel 205 of the coil channel selector 202 to the analog receiver 203 in the magnetic resonance systemiThe sum of the two terms is the column phase deviation
Step 103: by said line phase deviation
And column phase deviation
Obtaining the phase deviation of any input channel m204 from the coil unit 201 to the coil channel selector 202 to the analog receiver 203 via any output channel n205 in the magnetic resonance system
Obtaining the phase deviation matrix
Value of any one element of
In concrete implementation, the value of any element is calculated
There are various methods, one of which is shown below, for example.
In the embodiment of the invention, the line phase deviation is used
And column phase deviation
Obtaining the phase deviation of any input channel m204 from the coil unit 201 to the coil channel selector 202 to the analog receiver 203 via any output channel n205 in the magnetic resonance system
The method comprises the following steps:
with said line phase deviation
And column phase deviation
Respectively as a phase deviation matrix
A row reference value and a column reference value, the phase deviation being described by
Obtaining the phase deviation matrix
Value of any one element of
Wherein the content of the first and second substances,
phase deviation of line
Is selected to be the same as the row element of (a),
is a column phase deviation
Is selected from the group consisting of one column element of,
is a row-column cross element; m is a positive integer variable, n is a positive integer variable, M, N respectivelyFor the phase deviation matrix
The maximum number of rows and columns.
Wherein the line phase deviation is acquired
For obtaining said phase deviation matrix
First row phase deviation of
I.e. said any input channel j is selected as the first input channel; acquiring the column phase deviation
For obtaining said phase deviation matrix
Is different in phase from the first column
I.e. the any output channel i is selected as the first output channel;
wherein the content of the first and second substances,
the phase deviation
Is composed of
When embodied, by phase deviation
Constructed phase deviation matrix
There are various methods, one of which is shown below, for example.
In the embodiment of the invention, the phase deviation is calculated
Constructed phase deviation matrix
Comprises the following steps:
according to an embodiment of the present invention, the method for obtaining the phase deviation may also be applied to failure analysis of the radio frequency receiving link.
Another embodiment of the present invention provides a phase deviation acquiring system, which includes a row phase deviation acquiring module 310, a column phase deviation acquiring module 320, and a calculating module 330.
A line phase offset acquisition module 310 is used for acquiring the line phase offset of a coil unit 201 to any input channel j204 of a coil channel selector 202 in a magnetic resonance system from all output channels 205 to an analog receiver 203
A column phase offset obtaining module 320 is used for obtaining the column phase offset of all the input channels 204 from the coil unit 201 to the coil channel selector 202 via any output channel i205 to the analog receiver 203
A calculation module 330 for passing the line phase deviation
And column phase deviation
Calculating the phase deviation of any input channel m204 from the coil unit 201 to the coil channel selector 202 to the analog receiver 203 via any output channel n205 in the magnetic resonance system
Obtaining the phase deviation matrix
Value of any one element of
The row phase deviation acquiring module 310 and/or the column phase deviation acquiring module 320 further include a first measuring unit, a second measuring unit, and a summing unit.
A first measurement unit is used to measure the input phase offset from the coil unit 201 through any one of the input channels 204 of the coil channel selector 202 in the magnetic resonance system.
A second measurement unit is used to measure the phase deviation of the output from any one of the output channels 205 of the coil channel selector 202 to the analog receiver 203 in the magnetic resonance system.
A summing unit is used for calculating the sum of the input phase deviation and the output phase deviation for obtaining the row and/or column phase deviation.
Taking the row phase deviation obtaining module 310 as an example, the functions of the first measuring unit 311, the second measuring unit 312, and the summing unit 313 are explained. The line phase deviation obtained by the line phase deviation obtaining module 310
Comprising n line elements
Wherein the first measurement unit 311 is used for measuring the input phase deviation from the coil unit through the j-th input channel of the coil channel selector in the magnetic resonance system
A second measurement unit 312 is used for measuring an output phase deviation ω from the nth output channel of the coil channel selector to the analog receiver in the magnetic resonance systemnThe summing unit 313 is used to calculate the sum of the two terms, as shown in equation (1).
Since the phase values of the magnetic resonance system all satisfy the rules presented in formulas (1) to (4), the phase acquisition method of the embodiment of the present invention can also be applied to the fault analysis of the radio frequency receiving link. For example, a real system may have errors due to various reasons, and if the error is too far from ideal, it is likely to malfunction. Therefore, the method can also be applied to fault analysis, shortens the time of fault diagnosis and improves the accuracy of diagnosis results.
In order to shorten the time required for re-measuring the system phase deviation caused by replacing the system components at the customer site, another embodiment of the present invention provides a fast phase calibration method based on historical phase calibration data, that is, a fast calibration method of digital pattern matrix phase and a fast phase calibration system. With reference to fig. 2, 4 and 5, the method for fast calibrating the digital pattern matrix phase includes the following steps:
step 401: acquiring actual phase deviation theta ' of actual phase deviation matrix theta ' constituting a factory-delivered system 'mn。
In this embodiment, the actual phase deviation θ 'of the factory system is measured'mnThe method of (1) may be:
measuring the input phase offset from a coil unit 201 through the input channel 204 of a coil channel selector 202 in a factory-delivered magnetic resonance system
And measuringOutput phase offset ω 'from the output channel 205 of the coil channel selector 202 to an analog receiver 203'nWill input a phase deviation
And output phase deviation ω'nAdding the two to obtain the actual phase deviation theta 'of the factory system'mnNamely, the following formula (5):
wherein, theta'mnFor the actual phase deviation of the factory system,
is the input phase deviation, ω'nTo output the phase deviation.
Actual phase deviation theta 'as shown in formula (5)'mnThe method for decomposing into the input phase deviation and the output phase deviation is beneficial to the actual phase deviation theta'mnMeasured and ideal phase deviation theta ofmnFast calculation of (2).
The actual phase deviation θ 'from the factory magnetic resonance system'mnThe actual phase deviation matrix θ' formed can be expressed as the following equation (6):
wherein M is a positive integer, N is a positive integer, M is the maximum value of the number of rows of the matrix, N is the maximum value of the number of columns of the matrix, M is more than or equal to 1 and less than or equal to M, N is more than or equal to 1 and less than or equal to N,
an input phase deviation of an Mth input channel 204 from one coil unit 201 through one coil channel selector 202 in the magnetic resonance system; omega'NFor an Nth output channel 205 of the coil channel selector 202 to an analog receive in a magnetic resonance systemThe output of the machine 203 is phase offset.
From the above expression, the line phase deviation { θ'jnAnd column phase offset { theta'miThe methods are respectively as follows:
θ’jnis the line phase deviation { theta'jnOne row element of theta'miIs the column phase deviation { theta'miOne column element of.
Actual phase deviation θ 'as shown in equations (5) and (6)'mnThe method for decomposing into the input phase deviation and the output phase deviation is beneficial to the actual phase deviation theta'mnMeasured and ideal phase deviation theta ofmnFast calculation of (2).
In concrete implementation, the actual phase deviation theta 'of a factory-leaving system is calculated'mnThe actual phase deviation matrix θ' of the factory system formed by the method may be various, such as directly measuring the deviation of each position, or measuring the deviation generated by the coil channel selector 202 to obtain more accurate deviation value.
As shown in FIG. 2, the actual phase deviation θ 'of the factory system is obtained by a measurement method'mnFor example, the actual phase deviation theta 'of the factory system is obtained'mnMay include measuring an input phase deviation from the coil unit 201 to an input channel 204 of the coil channel selector 202 and measuring an output phase deviation from an output channel 205 of the coil channel selector 202 to the analog receiver 203, adding both the input phase deviation and the output phase deviation, i.e., an actual phase deviation θ 'of the factory system'mn. It is verified through experiments that the phase deviation of the coil channel selector 202 itself is negligible.
Above obtainingActual phase deviation of plant System θ'mnThe simplified model map and mathematical model of (a) are equally applicable to the acquisition of the field system phase deviation θ in step 406 "mn。
Step 402: a line phase deviation { theta ] by the actual phase deviation matrix thetajnAnd a column phase offset thetamiCalculating an ideal phase deviation theta forming an ideal phase deviation matrix thetamn。
Wherein the line phase deviation { theta }jnThe phase deviation of any input channel j from a coil unit to a coil channel selector in a factory system from all output channels to an analog receiver; the column phase deviation [ theta ]miAnd the phase deviation from any output channel i to the analog receiver is obtained by passing all input channels from the coil unit to the coil channel selector in a factory system.
In a specific implementation, an ideal phase deviation theta forming an ideal phase deviation matrix theta is calculatedmnThere are various methods, one of which is shown below, for example.
In the present embodiment, the ideal phase deviation θ is calculated in step 402mnThe method of (1) may be:
step 4021: with the actual phase deviation theta'mnThe line phase deviation of { theta'jnAnd the column phase offset { theta'miAs the line reference values { theta } of the ideal phase deviation matrix theta, respectivelyjn}(0<j is less than or equal to M) and column reference value [ theta ]mi}(0<i≤N)
Step 4022: the ideal phase deviation θ can be obtained by the following equation (7)mn：
θmn＝θmi+θjn-θji (7)
Wherein, { theta }jn}＝{θ’jn}；{θmi}＝{θ’mi}；
{θjn}＝{θj1,θj2,…,θjN}，(n＝1,2…N,0<j<M)；
{θmi}＝{θ1i,θ2i,…,θMi}，(m＝1,2…M,0<i<N)；
Wherein theta isjnIs a line reference value { thetajnOne row element of, thetamiIs a column reference value [ theta ]miOne column element of, thetajiIs a row-column cross element; thetamiValue of element, theta, representing column i, row mjnValue of element, theta, representing column n, row jjiThe element value of the jth row and ith column is represented, M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
The ideal phase deviation θ is obtained in step 402mnThe method can quickly calculate the ideal phase deviation theta based on the historical factory data of the systemmnAnd establishing a reference basis for the rapid calibration method.
The ideal phase deviation theta 'can be passed through the same as the mathematical model of the actual phase deviation matrix theta' of the shipped magnetic resonance systemmnAn ideal phase deviation matrix θ is obtained, which can be expressed as the following equation (8):
the ideal phase deviation θ obtained from step 4022mnThe phase deviation Δ θ in step 403 can be obtainedmn. Phase deviation delta thetamnMay be the actual phase deviation θ'mnDeviation from ideal phase thetamnAs shown in the following formulas (9) and (10):
Δθmn＝θ’mn-θmn (9)
i.e. delta thetamn＝θ’mn-(θmi+θjn-θij) (10)
A calculation method for establishing a phase deviation matrix through a formula (10) is realized by calculating an actual phase deviation theta'mnDeviation from ideal phase thetamnCan quickly obtain the phase deviation delta theta by taking difference values of elements at corresponding positionsmnAnd basic data are provided for the quick calibration method.
In this embodiment, the steps4021 the line phase deviation { θ'jnIs a first row phase deviation { theta 'of the actual phase deviation matrix theta'1nI.e. the any input channel j204 is selected as the first input channel 204; the column phase deviation { theta'miIs the phase of the first column of the actual phase deviation matrix theta is different by { theta'm1I.e. the said any output channel i205 is selected as the first output channel 205.
Wherein the first row phase deviation { theta'1nIs different from the first column in phase by { theta'm1Are the line reference values { theta } of the ideal phase deviation matrix theta, respectively1nAnd a column reference value [ theta ]m1H, the ideal phase deviation thetamnComprises the following steps:
θmn＝θm1+θ1n-θ11。 (11)
wherein the content of the first and second substances,
θ’1nis the line phase deviation { theta'1nOne row element of theta'm1Is the column phase deviation { theta'm1One column element of, theta1nIs a line reference value { theta1nOne row element of, thetam1Is a column reference value [ theta ]m1One column element of, theta11Is a row-column cross element;
{θ1n}＝{θ11,θ12,…,θ1N}，(n＝1,2…N,0<j<M)；
{θm1}＝{θ11,θ21,…,θM1}，(m＝1,2…M,0<i<N)；
wherein, thetam1The value of the element, theta, representing column 1, row m1nValue of element, theta, representing column n, line 111Representing the value of the element in row 1 and column 1, M being the maximum number of rows of the matrixThe value N is the maximum value of the number of columns of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
As shown in FIG. 2, the first row phase offset { θ'1nMay be the phase offset of a coil unit 201 in a magnetic resonance system via a first input channel 204 of a coil channel selector 202 via all N output channels 205 to an analog receiver 203; first column phase deviation { theta'm1May be the phase offset of all M input channels 204 in the magnetic resonance system via the first output channel 205 to the analog receiver 203.
The method reduces the calculation complexity of the ideal phase offset matrix, and only fits the complete ideal phase offset matrix through the actual phase offset values of the factory systems in a row and a column.
Step 403: calculating actual phase deviation theta'mnDeviation from ideal phase thetamnPhase deviation Δ θ ofmn。
In particular, the phase deviation Delta theta is calculatedmnThere may be a variety of methods, one of which is shown below, for example.
In the present embodiment, the phase deviation Δ θ in step 403mnIs the actual phase deviation theta'mnDeviation from ideal phase thetamnThe difference of (a) can be represented by the following formulas (8) and (9):
Δθmn＝θ’mn-θmn (12)
i.e. delta thetamn＝θ’mn-(θm1+θ1n-θ11) (13)
Step 404: obtaining a phase deviation Delta thetamnMaximum value of (a) Δ θmax。
The phase deviation Δ θ obtained by step 403mnIt can be known that the phase deviation values which coexist in M × N phases are the phase deviation value with the largest value, i.e. the phase deviation value with the largest value is delta thetamax。
Step 405: determining the maximum value Delta thetamaxWhether it is smaller than a preset threshold value delta. At said maximum value Δ θmaxIf the value is smaller than the preset threshold δ, go to step 406.
In the present embodiment, the setting of the preset threshold δ may have various criteria according to actual circumstances, for example, one of which is shown below.
The criteria for the preset threshold δ may be set as: when the maximum value of the phase deviation Delta thetamaxAnd when the value is less than the preset threshold value, the quality of the image is not obviously influenced.
In other embodiments, Δ θ is for a maximum valuemaxIn the case of not less than the preset threshold δ, operations other than step 406 may be performed according to actual conditions, and are not limited herein.
Step 406: one line phase deviation { theta } using a field system "jnAnd a column phase deviation { theta } "miCalculating the phase deviation theta of the field system "mn(ii) a From the field system phase deviation theta'mnAnd the constructed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system.
Wherein the line phase deviation { theta "jnThe method comprises the steps that (1) phase deviation of any input channel j from a coil unit to a coil channel selector in the field system to an analog receiver through all output channels is obtained; the column phase deviation [ theta ] "miThe phase deviation from any output channel i to the analog receiver is obtained by passing all input channels from the coil unit to the coil channel selector in the field system; wherein m is a positive integer variable and n is a positive integer variable.
In practice, at said maximum value Δ θmaxWhen the actual phase deviation is not less than the preset threshold value delta ', the actual phase deviation theta ' can be obtained 'mnThe method obtains the phase deviation theta of the field system "mn. One of the methods is to measure the phase deviation theta "mnEach element of (1).
In this embodiment, the phase deviation θ of the field system is measured "mnThe method comprises the following steps:
measuring the input phase deviation theta of M input channels 204 of a coil channel selector 202 from a coil unit 201 in a magnetic resonance system at the customer site "mnAnd the output phase deviation ω of the N output channels 205 to an analog receiver 203 "nAs followsFormula (14):
wherein, theta "mnIn order to be able to measure the phase deviation of the system in situ,
for inputting phase deviation, omega "nTo output the phase deviation.
The on-site system phase deviation θ shown by equation (14) "mnThe constructed field system phase deviation matrix θ ″ can be expressed by the following equation (15):
wherein the content of the first and second substances,
is the input phase deviation from the coil unit 201 through the mth input channel 204 of the coil channel selector 202 in the field system; omega "NThe output phase deviation from the Nth output channel 205 of the coil channel selector 202 to the analog receiver 203 in the magnetic resonance system is shown, M is a positive integer, N is a positive integer, M is the maximum value of the number of rows of the matrix, N is the maximum value of the number of columns of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
The description of measuring the phase deviation theta of the field system will be given by taking as an example a simplified model for measuring the phase deviation in a magnetic resonance system as shown in figure 2 "mnA method of (1).
Measuring phase deviation theta of field system "mnMay be for measuring an input phase deviation from the coil unit 201 to the input channel 204 of the coil channel selector 202 and for measuring an output phase deviation from the output channel 205 of the coil channel selector 202 to the analog receiver 203, the sum of the input phase deviation and the output phase deviation being the phase deviation θ "mn. It was verified through experiments that the phase of the coil channel selector 202 itselfThe deviation is negligible.
In one embodiment, when the maximum value Δ θ is greater thanmaxWhen the phase difference is smaller than the preset threshold value delta, the following calculation of the phase deviation theta of the field system can be adopted "mnFrom the phase deviation theta of the field system "mnAnd the constructed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system.
The concrete implementation is as follows:
one line phase deviation { theta } using a field system "jnAnd a column phase deviation { theta } "miCalculating the phase deviation theta of the field system "mn(ii) a From the field system phase deviation theta'mnAnd the constructed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system.
Wherein the line phase deviation { theta "jnThe phase deviation of any input channel j204 from a coil unit 201 to a coil channel selector 202 in the field system from all output channels 205 to an analog receiver 203; the column phase deviation [ theta ] "miThe phase deviation of any output channel i205 to the analog receiver 203 is taken from all input channels 204 of the coil unit 201 to the coil channel selector 202 in the field system; wherein m is a positive integer variable and n is a positive integer variable.
The on-site system phase deviation θ' is obtained by the following formula "mn：
θ”mn＝θ”mi+θ”jn-θ”ji (16)
Wherein, theta "miValue of the element, θ, representing the ith column, row m "jnValue of an element representing column n, line j, theta "jiThe element value of the jth row and ith column is represented, M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
From the field system phase deviation theta'mnThe constructed field system phase deviation matrix theta' is as follows:
wherein M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
Wherein the line phase deviation { theta "jnAnd column phase deviation { theta } "miCan be selected from the first row phase deviations { theta }respectively "1nAnd the first column phase deviation { theta } "m1The complete on-site system phase deviation theta can be obtained through the following formula (18) "mn
θ”mn＝θ”m1+θ”1n-θ”11 (18)
The method for obtaining the phase deviation of the field system by the above formula (18) adopts the same method as the method for obtaining the actual phase deviation of the factory system, namely, the phase deviations of a row and a column are measured firstly, then the phase deviations of other row and column positions are fitted, and the theoretical basis of the formula (18) is shown in the formulas (8) to (11).
As shown in fig. 2, the element values in the first row are input phase deviations of a coil unit 201 in the magnetic resonance system from all N output channels 205 to an analog receiver 203 via a first input channel 204 of a coil channel selector 202; the first column of element values is the output phase offset of all M input channels 204 in the magnetic resonance system via the first output channel 205 to the analog receiver 203.
In the present embodiment, the on-site system phase deviation θ ″, too, can be used "mnThe field system phase deviation matrix theta' is obtained by column fitting, and can be obtained by the following method:
obtaining phase deviation theta of field system "mnThe deviation of the nth column can be represented by the following formula (19):
fitting the n column deviations column by column to the field system phase deviation matrix θ "can be shown as equation (17).
The method for obtaining the field deviation matrix theta 'through the formula (19) reduces the calculation complexity of the field system phase deviation matrix theta', and only fits a complete ideal phase deviation matrix through field phase deviations of one row and one column. And the element values of the first row and the first column are more easily obtained, and the workload of field measurement is reduced.
Except for the above-mentioned field system phase deviation theta by fitting n columns "mnThe method can obtain the field system phase deviation matrix theta 'and can also obtain the field system phase deviation matrix theta' by other methods.
The calibration method of the digital mode matrix phase of the embodiment of the invention is a method for determining whether a rapid phase calibration method can be adopted or not based on historical phase calibration data, and can shorten the phase calibration time on the premise of ensuring the precision. Especially, when an engineer needs to obtain the phase deviation again on a client site due to hardware replacement, the method reduces the workload of client site measurement and debugging, and obviously improves the calibration efficiency of the site system phase deviation.
The calibration system of the digital mode matrix phase is also applied to the fault analysis of the radio frequency receiving link.
Since the phase values of the magnetic resonance system all satisfy the rules presented in equations (5) to (19), the system can also be applied to the fault analysis of the radio frequency receiving link. For example, a real system may have errors due to various reasons, and if the error is too far from ideal, it is likely to malfunction. Therefore, the method can also be applied to fault analysis, shortens the time of fault diagnosis and improves the accuracy of diagnosis results.
The calibration method of the digital pattern matrix phase in the embodiment of the present invention is described in detail above, and the calibration system of the digital pattern matrix phase in the embodiment of the present invention is described in detail below, and for details that are not disclosed in the embodiment of the system of the present invention, reference may be made to the description in the corresponding method embodiment.
Fig. 5 is a diagram illustrating an exemplary method for calibrating a digital pattern matrix phase according to an embodiment of the present invention. As shown in fig. 5, a system for calibrating a digital pattern matrix phase according to an embodiment of the present invention may include: an actual phase deviation obtaining module 510, an ideal phase deviation calculating module 520, a phase deviation calculating module 530, a maximum value obtaining module 540, a judging module 550 and a field system phase deviation module 560.
The actual phase deviation obtaining module 510 is configured to obtain an actual phase deviation θ ' of an actual phase deviation matrix θ ' constituting a factory system 'mn。
In this embodiment, the actual phase deviation obtaining module 510 may include: a first measurement unit 311, a second measurement unit 312 and a summation unit 313.
Wherein the first measurement unit 311 is used for measuring an input phase deviation from the coil unit 201 via the input channel 204 of the coil channel selector 202 in the magnetic resonance system
The second measurement unit 312 is used for measuring an output phase deviation ω 'from the output channel 205 of the coil channel selector 202 to the analog receiver 203 in the magnetic resonance system'n(ii) a The summing unit 313 is used to calculate the input phase offset
Is deviated from output phase by ω'nAnd (4) summing.
In the present embodiment, the actual phase deviation θ'mnCan be obtained by the formula (5).
Actual phase deviation theta 'as shown in formula (5)'mnThe method for decomposing into the input phase deviation and the output phase deviation is beneficial to the actual phase deviation theta'mnMeasured and ideal phase deviation theta ofmnFast calculation of (2).
The ideal phase deviation calculation module 520 is used to calculate the ideal phase deviation theta forming the ideal phase deviation matrix thetamn。
In this embodiment, the ideal phase deviation θ is calculated by the ideal phase deviation calculating module 520mnThe method can be carried out by the following method:
with the actual phase deviation theta'mnOne row of phaseBit deviation of { theta'jnAnd a column phase offset of { theta'miAs the line reference values { theta } of the ideal phase deviation matrix theta, respectivelyjn}(0<j is less than or equal to M) and column reference value [ theta ]mi}(0<i is less than or equal to N), the ideal phase deviation theta is obtained through the formula (7)mnObtaining any element value theta in the ideal phase deviation matrix thetamn。
The ideal phase deviation θ obtained by the above equation (7)mnOnly the element values of one row and one column in the actual phase deviation matrix theta' are needed, and the number of the reference element values is small, so that the calculation is convenient.
The phase deviation calculation module 530 is used for calculating an actual phase deviation theta'mnDeviation from ideal phase thetamnPhase deviation Δ θ ofmnAnd may be obtained by formula (9) and/or formula (10).
Calculation method for establishing phase deviation matrix through formula (9) and/or formula (10), and calculating actual phase deviation theta'mnDeviation from ideal phase thetamnCan quickly obtain the phase deviation delta theta by taking difference values of elements at corresponding positionsmnAnd basic data are provided for the quick calibration method.
The maximum value obtaining module 540 is used for obtaining the phase deviation delta thetamnMaximum value of (a) Δ θmax。
The determining module 550 is used for determining the maximum value Δ θmaxWhether it is smaller than a preset threshold value delta.
The field system phase deviation module 560 is used to determine the maximum value Δ θmaxWhen the phase difference is larger than a preset threshold value delta, an actual phase difference module is adopted to obtain the actual phase difference theta of the system'mnThe method obtains the phase deviation theta of the field system "mn(ii) a Or for at a maximum value Δ θmaxWhen the phase deviation is smaller than a preset threshold value delta, calculating the phase deviation theta of the field system by adopting a field system phase deviation module "mnFrom the phase deviation theta of the field system "mnAnd the constructed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system.
In this embodiment, when the maximum value Δ θ is setmaxWhen the difference is less than the preset threshold value delta,
measuring line phase deviation [ theta ] of field system "jnAnd column phase deviation { theta } "mi}；
Wherein the line phase deviation { theta "jnThe phase offset of any input channel j204 from a coil unit 201 to a coil channel selector 202, all output channels 205 to an analog receiver 203 in the field system.
Column phase deviation [ theta ] "miThe phase offset of any output channel i205 to the analog receiver 203 is taken from all input channels 204 of the coil unit 201 to the coil channel selector 202 in the field system. The on-site system phase deviation theta is obtained by formula (16) "mn。
Wherein the line phase deviation { theta "jnAnd column phase deviation { theta } "miCan be selected from the first row phase deviations { theta }respectively "1nAnd the first column phase deviation { theta } "m1Obtaining the on-site system phase deviation theta through a formula (18) "mn。
In this embodiment, the phase difference between the first row and the first column is used as the reference value, and the phase difference θ of the acquisition system is shortened "mnAnd the element value theta of the first line "1nAnd the value of the element of the first column theta "m1The values of the elements for other rows or columns are easier to measure.
From the in-situ system phase deviation theta' by equation (17) "mnA field system phase deviation matrix theta "is constructed.
The method for quickly calibrating the phase of the digital mode matrix is used for fitting a complete phase deviation matrix by acquiring the phase deviation data of one row and one column of a field system on the basis of factory phase calibration data and on the premise of ensuring the accuracy, namely on the premise of meeting a preset threshold value.
The method for rapidly calibrating the digital mode matrix phase is applied to the magnetic resonance system to calibrate the phase of the system, and the magnetic resonance system meets the rule, so the method can also be applied to the fault analysis of a radio frequency receiving link.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (25)
1. A phase offset acquisition method, comprising:
obtaining a line phase offset from a coil unit to any input channel j of a coil channel selector in a magnetic resonance system via all output channels to an analog receiver
And acquiring a column phase deviation of all input channels from the coil unit to the coil channel selector from any output channel i to the analog receiver
By said line phase deviation
And column phase deviation
Obtaining the phase deviation from any output channel n to the analog receiver from any input channel m from the coil unit to the coil channel selector in the magnetic resonance system
Obtaining the phase deviation matrix
Value of any one element of
Wherein i, j, m and n are positive integers respectively.
2. The method of claim 1, wherein the line phase deviation is passed
And column phase deviation
Obtaining the phase deviation from any output channel n to the analog receiver from any input channel m from the coil unit to the coil channel selector in the magnetic resonance system
The method comprises the following steps:
with said line phase deviation
And column phase deviation
Respectively as a phase deviation matrix
A row reference value and a column reference value, the phase deviation being described by
Obtaining the phase deviation matrix
Value of any one element of
Wherein the content of the first and second substances,
phase deviation of line
Is selected to be the same as the row element of (a),
is a column phase deviation
Is selected from the group consisting of one column element of,
is a row-column cross element;
m is a positive integer variable, n is a positive integer variable, M, N is the phase deviation matrix respectively
The maximum number of rows and columns.
3. The method of claim 2, wherein the phase deviation matrix
Comprises the following steps:
4. the method of claim 2, wherein the one row element is obtained
The method comprises the following steps: measuring an input phase offset from the coil unit through a jth input channel of the coil channel selector in the magnetic resonance system
And measuring an output phase deviation omega of the magnetic resonance system from the nth output channel of the coil channel selector to the analog receivernThe sum of the two terms is the line phase deviation
Element of (5)
Obtaining the one column element
The method comprises the following steps: measuring an input phase deviation from the coil unit through an m-th input channel of the coil channel selector in the magnetic resonance system
Andmeasuring an output phase deviation ω from an ith output channel of the coil channel selector to the analog receiver in the magnetic resonance systemiThe sum of the two terms is the column phase deviation
Column element of (1)
5. The method of claim 2, wherein the any input channel j is a first input channel; the any output channel i is a first output channel;
wherein the content of the first and second substances,
the phase deviation
Is composed of
6. The method of claim 1, wherein the method is further applied to failure analysis of a radio frequency receive link.
7. A phase deviation acquisition system, comprising:
a line phase deviation obtaining module for obtaining any input channel j from a coil unit to a coil channel selector in a magnetic resonance system from all output channels to an analog receiverLine phase deviation of
A column phase deviation obtaining module for obtaining the column phase deviation from all the input channels from the coil unit to the coil channel selector to the analog receiver via any output channel i
A calculation module for passing the line phase deviation
And column phase deviation
Calculating the phase deviation from any output channel n to the analog receiver from any input channel m from the coil unit to the coil channel selector in the magnetic resonance system
Obtaining the phase deviation matrix
Value of any one element of
Wherein i, j, m and n are positive integers respectively.
8. The system of claim 7, wherein the row phase offset acquisition module and/or the column phase offset acquisition module further comprises:
a first measuring unit for measuring an input phase deviation from the coil unit through any one of the input channels of the coil channel selector in the magnetic resonance system;
a second measuring unit for measuring the phase deviation of the output from any output channel of the coil channel selector to the analog receiver in the magnetic resonance system; and
a summation unit for calculating the sum of the input phase deviation and the output phase deviation to obtain the line phase deviation
And/or said column phase deviation
9. A method for calibrating a phase of a digital pattern matrix, comprising:
acquiring actual phase deviation theta ' of actual phase deviation matrix theta ' constituting a factory-delivered system 'mn；
A line phase deviation { theta ] by the actual phase deviation matrix thetajnAnd a column phase offset thetamiCalculating an ideal phase deviation theta forming an ideal phase deviation matrix thetamn；
Calculating the actual phase deviation theta'mnDeviation from said ideal phase θmnPhase deviation Δ θ ofmn：
Obtaining the phase deviation Delta thetamnMaximum value of (a) Δ θmax；
At said maximum value Δ θmaxWhen the phase deviation is smaller than a preset threshold value delta, a line phase deviation { theta ] of a field system is adopted "jnAnd a column phase deviation { theta } "miCalculating the phase deviation theta of the field system "mnn(ii) a From the field system phase deviation theta'mnAnd the constructed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system.
10. The calibration method according to claim 9, further comprising:
at said maximum value Δ θmaxWhen the actual phase deviation is not less than a preset threshold value delta ', the actual phase deviation theta ' is obtained 'mnThe method obtains the phase deviation theta of the field system "mn。
11. Calibration method according to claim 9, characterised in that said actual phase deviation θ'mnComprises the following steps:
measuring input phase deviation from coil unit through input channel of coil channel selector in factory system
And an output phase offset ω 'from an output channel of the coil channel selector to an analog receiver'nWill input a phase deviation
And output phase deviation ω'nAdding the two to obtain the actual phase deviation theta 'of the factory system'mn：
Wherein, theta'mnFor the actual phase deviation of the factory system,
is the input phase deviation, ω'nTo output the phase deviation.
12. The calibration method according to claim 11, wherein the actual phase deviation matrix θ' is:
wherein the content of the first and second substances,
the input phase deviation of the Mth input channel passing through the coil channel selector from the coil unit in the magnetic resonance system; omega'NThe output phase deviation of the magnetic resonance system from the Nth output channel of the coil channel selector to the analog receiver is obtained, M is the maximum value of the row number of the matrix, and N is the maximum value of the column number of the matrix;
line phase deviation { theta 'of actual phase deviation matrix theta'jnAnd column phase offset { theta'miThe methods are respectively as follows:
θ’jnis the line phase deviation { theta'jnOne row element of theta'miIs the column phase deviation { theta'miOne column element of.
13. Calibration method according to claim 12, characterized in that said ideal phase deviation θmnComprises the following steps:
with the actual phase deviation theta'mnThe line phase deviation of { theta'jnAnd the column phase offset { theta'miAs the line reference values { theta } of the ideal phase deviation matrix theta, respectivelyjn}(0<j is less than or equal to M) and column reference value [ theta ]mi}(0<i ≦ N), the ideal phase deviation θ is obtained by the following equationmnObtaining any element value theta in the ideal phase deviation matrix thetamn：
θmn＝θmi+θjn-θji
Wherein, { theta }jn}＝{θ’jn}；{θmi}＝{θ’mi}；
{θjn}＝{θj1,θj2,…,θjN}，(n＝1,2…N,0<j<M)；
{θmi}＝{θ1i,θ2i,…,θMi}，(m＝1,2…M,0<i<N)；
Wherein theta isjnIs a line reference value { thetajnOne row element of, thetamiIs a column reference value [ theta ]miOne column element of, thetajiIs a row-column cross element; thetamiValue of element, theta, representing column i, row mjnValue of element, theta, representing column n, row jjiThe element value of the jth row and ith column is represented, M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
14. Calibration method according to claim 13, characterized in that the line phase deviation { Θ'jnIs a first row phase deviation { theta 'of the actual phase deviation matrix theta'1nThe input channel j is a first input channel; the column phase deviation { theta'miIs the phase of the first column of the actual phase deviation matrix theta is different by { theta'm1The output channel i is a first output channel;
wherein the first row phase deviation { theta'1nIs different from the first column in phase by { theta'm1Are the line reference values { theta } of the ideal phase deviation matrix theta, respectively1nAnd a column reference value [ theta ]m1H, the ideal phase deviation thetamnComprises the following steps:
θmn＝θm1+θ1n-θ11。
15. calibration method according to claim 9, characterized in that the phase deviation Δ θmnComprises the following steps:
Δθmn＝θ’mn-(θm1+θ1n-θ11)。
16. according to the claimsThe calibration method according to claim 9, wherein the maximum value Δ θ is setmaxWhen the phase deviation is smaller than a preset threshold value delta, calculating the phase deviation theta of the field system "mnComprises the following steps:
measuring a line phase deviation of a field system [ theta ] "jnAnd a column phase deviation { theta } "mi}；
The on-site system phase deviation θ' is obtained by the following formula "mn：
θ”mn＝θ”mi+θ”jn-θ”ji
The line phase deviation [ theta ] "jnThe method comprises the steps that (1) phase deviation of any input channel j from a coil unit to a coil channel selector in the field system to an analog receiver through all output channels is obtained; the column phase deviation [ theta ] "miThe phase deviation from any output channel i to the analog receiver is obtained by passing all input channels from the coil unit to the coil channel selector in the field system;
wherein, theta "miValue of the element, θ, representing the ith column, row m "jnValue of an element representing column n, line j, theta "jiThe element value of the jth row and ith column is represented, M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
17. The calibration method according to claim 16, wherein the phase deviation θ 'is determined by the field system phase deviation θ'mnThe constructed field system phase deviation matrix theta' is as follows:
wherein M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
18. Calibration method according to claim 10, characterised in that the actual phase deviation θ 'is obtained'mnThe method obtains the phase of the field systemDeviation theta'mnComprises the following steps:
measuring input phase deviation of input channel from coil unit through coil channel selector in field system
And an output phase deviation omega from the output channel of the coil channel selector to an analog receiver "nNamely:
wherein, theta "mnIs the actual phase deviation of the field system,
for inputting phase deviation, omega "nTo output the phase deviation.
19. The calibration method according to claim 18, wherein the field system phase deviation matrix θ "is:
wherein the content of the first and second substances,
an input phase deviation of an Mth input channel passing through the coil channel selector from the coil unit in a field system; omega "NAnd M is the maximum value of the row number of the matrix, and N is the maximum value of the column number of the matrix.
20. A system for calibrating a digital pattern matrix phase, comprising:
an actual phase deviation obtaining module for obtaining the actual phase deviation theta 'of the factory system forming the actual phase deviation matrix theta'mn；
An ideal phase deviation calculation module for calculating an ideal phase deviation theta forming an ideal phase deviation matrix thetamn；
A phase deviation calculation module for calculating the actual phase deviation θ'mnDeviation from said ideal phase θmnPhase deviation Δ θ ofmn：
Δθmn＝θ’mn-θmn；
A maximum value obtaining module for obtaining the phase deviation delta thetamnMaximum value of (a) Δ θmax；
A judging module for judging the maximum value delta thetamaxWhether the difference is smaller than a preset threshold value delta: and
a field system phase deviation module for calculating a maximum value Δ θmaxWhen the phase deviation is smaller than a preset threshold value delta, the phase deviation theta of the field system is calculated by adopting the phase deviation module of the field system "mnFrom the field system phase deviation θ "mnThe formed field system phase deviation matrix theta' is used for carrying out phase calibration on the field system; wherein m and n are respectively positive integer variables.
21. The calibration system of claim 20, wherein: the actual phase deviation acquisition module includes:
a first measuring unit for measuring the input phase deviation of the factory system from the coil unit via any input channel of the coil channel selector
A second measurement unit for measuring output phase deviation ω 'from any output channel of the coil channel selector to the analog receiver'n(ii) a And
a summation unit for calculating actual phase deviation θ'mnI.e. input phase deviation
Is deviated from output phase by ω'nAnd (3) the sum:
22. the calibration system of claim 20, wherein: actual phase deviation of θ'mnThe actual phase deviation matrix θ' is formed as:
wherein the content of the first and second substances,
the input phase deviation of the Mth input channel from the coil unit through the coil channel selector in the magnetic resonance system; omega'NThe output phase deviation from the Nth output channel of the coil channel selector to the analog receiver in the magnetic resonance system is shown, wherein M is the maximum value of the row number of the matrix, and N is the maximum value of the column number of the matrix;
line phase deviation { theta 'of actual phase deviation matrix theta'jnAnd column phase offset { theta'miThe methods are respectively as follows:
θ’jnis the line phase deviation { theta'jnOne row element of theta'miIs the column phase deviation { theta'miOne column element of.
23. The calibration system of claim 22, wherein the ideal phase offset calculation module is configurable to:
with the actual phase deviation theta'mnThe line phase deviation of { theta'jnAnd the column phase offset { theta'miAs the line reference values { theta } of the ideal phase deviation matrix theta, respectivelyjn}(0<j is less than or equal to M) and column reference value [ theta ]mi}(0<i ≦ N), the ideal phase deviation θ is obtained by the following equationmnObtaining any element value theta in the ideal phase deviation matrix thetamn：
θmn＝θmi+θjn-θji
Wherein, { theta }jn}＝{θ’jn}；{θmi}＝{θ’mi}；
{θjn}＝{θj1,θj2,…,θjN}，(n＝1,2…N,0<j<M)；
{θmi}＝{θ1i,θ2i,…,θMi}，(m＝1,2…M,0<i<N)；
Wherein, thetajnIs a line reference value { thetajnOne row element of, thetamiIs a column reference value [ theta ]miOne column element of, thetajiIs a row-column cross element; m is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
24. The calibration system of claim 20, wherein the field system phase offset calculation module:
for interpreting the maximum value Delta theta in the decision modulemaxWhen the line phase deviation is smaller than a preset threshold value delta, measuring the line phase deviation { theta'jnAnd column phase deviation { theta } "mi}；
Wherein the line phase deviation { theta "jnIs a coil in the field systemPhase deviation of any input channel j from a coil channel selector to an analog receiver via all output channels;
column phase deviation [ theta ] "miThe phase deviation from any output channel i to the analog receiver is obtained by passing all input channels from the coil unit to the coil channel selector in the field system;
the on-site system phase deviation θ' is obtained by the following formula "mn：
θ”mn＝θ”mi+θ”jn-θ”ji
Wherein the line phase deviation { theta "jnThe method comprises the steps that (1) phase deviation of any input channel j from a coil unit to a coil channel selector in the field system to an analog receiver through all output channels is obtained; the column phase deviation [ theta ] "miThe phase deviation from any output channel i to the analog receiver is obtained by passing all input channels from the coil unit to the coil channel selector in the field system; theta'miValue of the element, θ, representing the ith column, row m "jnValue of an element representing column n, line j, theta "jiThe element value of the jth row and ith column is represented, M is the maximum value of the row number of the matrix, N is the maximum value of the column number of the matrix, M is more than or equal to 1 and less than or equal to M, and N is more than or equal to 1 and less than or equal to N.
25. The calibration system of claim 21, wherein the field system phase offset module:
also for at said maximum value Δ θmaxWhen the phase difference is larger than a preset threshold value delta, the actual phase difference module is adopted to obtain the actual phase difference theta'mnThe method obtains the phase deviation theta of the field system "mn。
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